Rock drill with blowing device



May 17, 1938. E. B. Lr-:AR

ROCK DRILL WITH BLOWING DEVICE Filed June 5, 193s s sheets-sheet 1INVENTOR May 17, 1938. E. B. LEAR u ROCK DRILL WITH BLOWING DEVICE FiledJune 3, 1936 3 Sheets-Sheet 2 INVENTOR ATTO R N EY May 17, 193s. E. B.LEAR 2,117,810

. ROCK DRILL WITH BLOWING DEVICE Filed June 5, 195s s sheets-sheet sATTORNEY Patented May 17, 1938 VVUNITE-D 'STATES Pneumatic Tool Company,New

York, N. Y., a

corporation of New Jersey 'Application June 3,

1 Claim.

The present invention relates to fluid pressure operated percussivetools, such as rock drills, and is concerned particularly with thethrottle .and distributing valves for such tools.

Among the objects of the invention are to reduce the manufacturing costand weight of a rock drill and to insure positive hole cleaning.Accordingly, a throttle Valve and a blower valve are combined into aunitary structure so arie ranged that each time the throttle valve isturned on or off a stream of air is directed through the bore in thedrill steel to remove the detritus from the hole. The throttle valve isso constructed thatit closes the central exhaust port for the l cylinderwhenever the throttle valve is in either the blowing or closed positionto prevent the admissionA of dirt through the exhaust port to thecylinder bore.

A feature of the invention resides in fluid pressure means for holdingthe distributing valve immovable against one of its seats to admitcompressed air to the rear end of the cylinder bore from whence the airis conducted through the hollow piston to the drill steel bore with aVminimum of leakage. The means for holding the distributing valve inposition comprises ports in a manipulative throttle valve, one of whichadmits live air lto one face of the distributing valve and another ofwhich exhausts the opposingY face of the distributing valve.

Another object ofthe invention is the provision of a distributing valveof the disc Atype having means for centering the valve relative to itsseats and for prolonging the life of the valve. The vdistributing valveis in the form of a disc perforated to receive a bushing and'having ahub adapted to fit the bushing and guide the valve in its movement.

Other objects and features of the invention will appear more clearlyfrom the accompanying `drawings and appended claim.

In the drawings which illustrat ment of the invention:

Fig. 1 is an elevation of a portion of a rock drill ofthe sinker type,the throttle valve handle being shown in drilling position;

Fig. 2 is a section through the plane indicated by the arrows 2-2 inFigs. 1 and 6;

Fig. 3 is a view similar to Fig. 2 but partly in elevation .and partlyschematic and showing the combined throttle and blower valve in blowingposition; Y

Fig. 4l isa fragmentary schematic view showing twodiiierentsections ofthe throttle valve e one embodi- 1936, .Serial No. 83,210

and associated ports, the valve being arranged in the ori-position;

Fig. 5 is a View similar to Fig. 4 but with the throttle valve adjustedto the drilling position;

Fig. 6 is an end elevation looking from lefttoward right in Fig. 1;

Fig. '7 is a cross-section as. indicated by the arrows l-'I in Fig. 1,but with the throttle valve in blowing position;

Fig. 8 is a fragmentary longitudinal section showing the cylinder,piston and distributing valve, certain passages being, for convenience,shown in simplified form;

Fig. 9 is a fragmentary longitudinal sectional view on an enlarged scaleshowing the distributing Valve and valve chest, and

Fig. 10 is a sectional view of the distributing valve on the same scaleas Fig. 9.

The rock drill illustrated in the drawings comprises a cylinder IIhaving a piston I2 reciprocably mounted therein. The forward part of thepiston has a grooved extension I3 which passes through a front cylinderwasher I4 and into fluted engagement with an internally grooved chucknut I5 which iskeyed to a chuck i6. The washer I4 forms a closure forthe front end of the cylinder. At the end of its forward stroke thepiston strikes the drill steel I1 having a non-circular t with thechuck. The chuck nut I5, chuck I6, and washer I4 are held in position bymeans of a iront head I9 which may be fastened to the cylinder by anysuitable means, such asA elongated bolts I8 shown in Figs. l, 6 and '7.

The rear of the cylinder II is closed by a back cylinderwasher whichcooperates with a valve case 2l to form a housing for a distributingvalve 22. A ratchet ring 23 is. positioned between the valve case and abackhead 24, the backhead being adapted to seat the heads Ia of thebolts I8. The backhead is provided with arms 25 for supporting a griphandle 26. A plate 2l at the rear end of the ratchet ring cooperateswith the backhead 24 to provide a lubricant reservoir. 28.

Any suitable means may be provided for ro* tating the piston I2step-by-step as it reciprocates. As shown, the rotating mechanismcomprises a riiie nut Sil screwed to the piston, a rifle bar 3l spirallysplined to the nut, and pawls 32 carried by the head of the rie bar andengageable with the internally toothed ratchet ring 23. A bushingf33,surrounding the rifle bar, provides a support for valve 22.

The distributing valve 22 is shown most clearly in Figs. 9and 10. Itcomprises a disk portion.35

and a hub 36 integral therewith. The forward face of the disc portion isa plane surface adapted to rest on one or the other of the seats 31]cand 311* formed on the member 20. Valve seats 313 and 317 are at andangularly disposed relative to each other so that the planes of theseats diverge forwardly. The seats have recesses 38]c and 38T. A port 40connects the recess 38T with the rear end of the cylinder and a passage4| connects recess 38j with the front end of the cylinder thereby toadmit live pressure fluid alternately to opposite sides of the pistonhead I2.

The interior of the hub 35 is dened by frustoconical surfaces 36a and351), the included angle between such surfaces being equal to theincluded angle between the seatsl 31j and 317 so that the interior ofthe hub embraces. the bushing 33 on opposite sides when the disc portion35 rests on either seat. The upper edge 35e of the hub is bevelled toiit the adjacent portion of the valve chest 2|. The hub 36 guides thevalve in its movement, permits rapid tripping of the valve and prolongsthe life of the same. The hub also centers the valve with respect toVits seats and associated passages and thereby insures an adequatesupply of pressure fluid with minimum leakage. The valve 22 is free tobe oriented about its axis to distribute wear.

When the machine is conditioned for drilling, the operation is asfollows: Live air is admitted (by throttle means hereinafter described)to a chamber 43 in the valve housing 253, 2i, the rear face of thedistributing valve 22 being exposed to pressure fluid in said chamber.Assuming the distributing valve and piston occupy the position shown inFigs. 8 and 9, live air passes around the peripheral edge of the valvedisc portion 35 over the seat 31T and through recess 381 and port 4|! tothe rear end of the cylinder, thereby forcing the piston l2 forwardly.The air in front of the piston head I2 is vented through exhaust port 44until the piston head has covered the exhaust port. The piston continuesmoving forward under its momentum and delivers a blow to the drill steell1. Toward the end of the forward stroke of the piston the valve istripped to the position shown in Fig. 2 by the combined action of areduction in pressure in the recess 38T caused by the uncovering of theexhaust port 44, and the building up of pressure at the front end of thecylinder due to the compression of air trapped in front of the pistonhead I2 which is transmitted to the recess 38]c by means of passage 4|.After the valve has been tripped, live pressure fluid from chamber 43passes around the peripheral edge of the distributing valve over seat31j and through recess 38j and passage 4| to the front end of thecylinder to force the piston rearwardly. The air at the rear end of thecylinder is first exhausted through port 44 and then compressed afterythe piston head covers the exhaust port. When the front edge of thepiston head uncovers the exhaust port, the drop in pressure at the frontend of the cylinder causes a corresponding reduction in pressure in therecess 38f which, together with the increase of pressure in recess 381",is effective to trip the valve to the position shown in Fig. 9, thuscompleting a cycle of operation.

It is desirable to provide means for blowing a stream of live airthrough the drill steel I1 to clear the bore hole of accumulateddetritus. Accordingly, the invention comprises a blowing arrangementwhich is operable whenever the throttle valve is turned on or 01T andwhich does not require the manipulation of any device other than thethrottle valve.

The throttle valve 45, as shown in Fig. 7, is generally offrusto-conical shape to fit a correspondingly shaped bore in aprojection 46 on the outside of the cylinder A handle 41, having anextension on the valve, is keyed thereto at 48 and is retained by a nut49 threaded on the extremity of the throttle valve. A spring-presseddetent 50 carried by the handle is adapted to register with any one ofthree depressions on the cylinder projection 46 for yieldingly lockingthe handle and valve in selected position of adjustment. A sleeve 53threaded to the cylinder projection 46, provides a retainer for an airsupply hose 54 which communicates with recess 55 in the throttle valve.

As shown in Figs. 3, 4 and 5, the live air recess 55 communicates withtwoports in the throttle valve 45 adapted selectively to admit pressurefluid to passage 51 leading to the supply chamber 4S in the distributingvalve housing 20, 2|. One of these ports 58 registers with passage 51 inthe drilling position and the other port 59 registers in the blowingposition. The throttle valve 45 has a groove Eil out oi communicationwith the live air recess 55 and positioned to connect the main exhaustport 44 with the exhaust port 6| in the projection 46 when the throttlevalve is adjusted to drilling position. A supplementary groove 60aestablishes communication between exhaust port 6| and a passage 63leading to recess 38j in the distributing valve housing 2l to vent therecess when the throttle valve is adjusted to blowing position.

When the throttle handle 41 is in the drilling position, shown in Figs.1 and 2, live air is supplied to the distributing valve case 2| throughport 58 in the throttle valve and passage 51 in the cylinder. At thesame time the central exhaust port 44 in the cylinder is vented throughgroove 65 in the throttle valve. In order to stop the operation of themachine, the throttle handle 41 must first be turned to the blowingposition shown in Figs. 3 and 7. In this position, the throttle valvesupplies live air to the distributing valve chamber 43 by means of port59` and passage 51. Simultaneously the central exhaust port 44 in thecylinder is closed by the throttle valve, and the recess 38j, facing oneside of the distributing valve, is vented through cylinder passage 63and throttle valve -grooves 60a and 60. The preponderance of pressure onthe rear face of that portion oi the distributing valve which overliesrecess 38j moves the valve to the position shown in Fig. 9 and holds thevalve against seat 31j to admit live pressure uid through port 40 to therear end of the cylinder. The pressure fluid admitted through port 4|)drives the piston forwardly until it is stopped by engagement with thedrill steel. Pressure uid in back of the piston passes through theclearance between the splines on the rifle bar 3| and rie nut 30 andthrough the interior of the hollow piston and drill steel to blow thedetritus from the bore hole. When the valve handle 41 is adjusted to theoff position, the live air recess 55 in the throttle valve is cut offfrom communication with the cylinder passages, and the main exhaust port44 in the cylinder is closed to prevent the admission of dust to theinterior of the cylinder.

What is claimed is:

A fluid actuated rock drill comprising a cylinder, a hollow pistonreciprocating therein, a hol- 2,117,810 low drill steel adapted toreceive blows from the valve, a manipulative throttle valve mountedpiston, a distributing valve chest, passages leadtherein, characterizedin that said throttle valve and housing are provided with selectivelyoper-- able means for venting either exhaust port and simultaneouslyclosing the other exhaust port, and vice versa, and are provided withselectively operable means for opening and closing the connectionsbetween the source of live pressure fluid and the supply chamber in thedistributing valve chest.

ing from said chest to the respective ends of the cylinder, a mainexhaust port for the cylinder, a supplementary exhaust port for thefront end of the cylinder, a fluid pressure supply chamber in the valvechest, a distributing valve in the chest controlling communicationbetween said supply chamber and said passages, a source of live pressurefluid, connections between said source and said supply chamber, ahousing for a throttle EARL B. LEAR.

